We propose to study the effects of chemotherapy and immunotherapy on immunity towards autochthonous or allogeneic tumor cells ("tumor-specific" immunity) in patients with a solid tumor or acute leukemia. A large proportion of the tumor cells obtained by biopsy will be stored in DMSO at minus 70 degrees, to permit replacement of tissue cultures after 3 month continuous passage to minimize nonspecific lysis. Blood mononuclear cells and serum will be obtained weekly or biweekly from each patient before, during and after therapy in studies ranging from 6 weeks to 2 years. Clinical response to therapy will be measured objectively. Cell-mediated cytotoxicity will be measured by a 48-hour assay in 16 mm diameter plastic wells, with 3H-proline or 125IUdR-labeled tumor cells. Blocking factor will be estimated by preincubating serum and tumor cells before adding mononuclear cells. Cytophilic antibodies will be titrated by the arming of mouse monocytes to form rosettes with tumor cells, while related antibody sensitizing for antibody-dependent cellular cytotoxicity (ADCC) will be titrated by the arming of neutral human monocytes to lyse tumor cells. "Nonspecific" cytotoxicity will be studied by examining stratified populations of "normal" individuals for reactivity, and by determining whether continuously cultivated tumor cells become overly sensitive to lysis. Which subpopulations of mononuclear cells are the major cytotoxic effectors will be studied and their specificity determined. Lymph node cells of melanoma patients receiving intralymphatic immunotherapy with MER will be compared with blood lymphocytes. Patients with acute myelocytic leukemia given immunotherapy will be studied to discern whether humoral immunity to the leukemia is improved. We hope to determine whether our current regimens of tumoricidal therapy are suppressive towards tumor-specific immunity, and whether putative immunotherapeutic regimens are stimulatory.